1. Field of the Invention:
The present invention relates to a tire cord fluid finish composition and method for finishing polyester cord, and is further related to the resultant cord and tires produced therewith.
2. Description of the Prior Art:
In the processing of filamentary material, it has been recognized by all those concerned that the development and application of critically selected ingredients with specific intrinsic properties in an homogenous blend or finish is essential to develop the full latent potential of the polyester fibers as a valuable and reliable tire cord. These fluids typically comprise lubricants, emulsifiers and wetting agents, plus additional ingredients necessary to assist in processing of the materials. The required properties of such individual materials and their beneficial effect on one another are well known to those versed in the art. Such properties are good fiber to fiber and fiber to metal lubricity; adequate but not excessive, also static suppression, good rubber adhesion, ability to form stable aqueous emulsions of less than one micron size, excellent wetting of the fiber, and complete compatibility with the resorcinol formaldehyde latex and other "dips" used in the process of adhering fiber to rubber. These and other more esoteric properties are essential to the manufacture of safe tires for automobiles, "off the road" construction and wheeled military armaments and carriers, airplane tires, etc. These properties are also important for other items such as hoses, V belts, rovolving belts as people carriers, post office and other conveyor belts, etc.
The problems and parameters involved in processing filamentary material are discussed in detail in U.S. Pat. No. 3,687,721, issued to Dardoufas on Aug. 29, 1972, and this discussion is incorporated herein by reference. As noted in the Dardoufas patent, a method and composition to allow proper wettability and lubricity is necessary for the preparation of improved industrial yarns. Further, emulsifiers having a proper HLB, hydrophilic-lipophilic balance, are important. Also, the treating fluid components must be capable of resisting heat treatment of temperatures perhaps as high as 250.degree. C. without volatizing or significantly altering the lubricity, stability and functionality of the fluid. The blended fluid ingredients should provide good lubricity to avoid abrasion and wearing of the filamentary material or the processing equipment. The use of antioxidants is also helpful to assist in resisting aging and heat deterioration of the filaments and finish.
There has been a withdrawal from the market of some chief finishes based on fossil fuel derivatives. Such finishes and others have formed highly undesirable resinous deposits on hot metal processing equipment. In addition such fossil fuel derivatives often do not possess sufficient inherent high thermal stability to meet new demands of federal and state regulatory agencies in respect to emissions from rubber tire manufacturing plants. A new composition to answer such problems is desirable, particularly one based on readily renewable and readily available raw materials annual agricultural sources of vegetable and animal fats and oils. Fossil fuels are not replaceable, subject to other uses or higher priorities and subject to escalating costs.
The present invention overcomes three important problems currently facing those concerned with producing satisfactory finishes for polyester yarn used in rubber tires for automobiles, etc. First, one of the very best and widely used fossil fuel derivatives for polyester tire cord purposes is no longer domestically available due to the "energy crunch". The present invention supplies a replacement based on continually replenished natural fats and oils. Second, current finishes often suffer from a propensity to polymerize into hard black water-insoluble deposits on hot metal equipment forcing shut down of equipment for cleaning. The addition of strong alkali is sometimes recommended, while another answer is the use of steam-cleaning jets to keep equipment clean. The present invention requires no such auxiliary measures, which introduce expense and other problems. Third, the present invention provides a thermally stable product that will not contravene the rules of state regulatory agencies in respect to emissions from rubber tire manufacturing plants as shown in Guideline Series: Measurement of Volatile Organic Compounds, United States Environmental Protection Agency, Office of Air Quality Planning & Standards, EPA-450/2-78-041, OAQPS No. 1.2-115 rev Sept. 79.
For many years hexadecyl or isocetyl stearate has been a preferred lubricant for use in tire yarn finishes, as much as 75% being used in the compounded formulation. Due to the "energy crunch" it is no longer readily available. A new finish must be found of which continuous delivery can be assured. The popularity of hexadecyl stearate and other esters of hexadecyl alcohol for this purpose is attested to in U.S. Pat. Nos. 3,428,560, issued to Olsen on Feb. 18, 1969; 3,575,856, issued to Anton on Apr. 20, 1971; 3,687,721, issued to Dardoufas on Aug. 29, 1973; 3,730,892, issued to Marshall and Dardoufas on May 1, 1973; and 3,850,658, issued to Gomez et al. on Nov. 26, 1974. The expense of evaluating a new finish for tire cord purposes is an extremely lengthy and expensive operation. The unavailability of a satisfactory and proven lubricant in self-emulsifiable form represents a serious economic loss.
As is evidenced by the prior art, a variety of finish compositions have been proposed for use with various filamentary materials. The present invention provides a finish composition particularly adapted for use with polyester cord. The term cord is used herein to include the variety of filamentary forms of the polyester material, whether it be filaments, fibers, yarns, threads or similar forms. The present invention further provides a method for the treating of polyester cord, and a resulting cord which is advantageous for processing in normal fashion.
The prior art has concerned itself chiefly with finding a satisfactory lubricant to impart to the fiber sufficient lubricity to slide over metal, wood and plastic surfaces without cutting such surfaces or being abraded by them. A further concern is to supply just sufficient lubricity to all the individual fibers so that they can slide over one another and yet have sufficient cohesion that filaments would stay together as a collection of filaments in yarn form and not slough off packaged yarns. Emulsifiers and antistatic agents must be found to facilitate the preparation of stable emulsions. In the prior art the chief lubricants have been: mineral oil, carefully selected and/or rearranged glycerides of C.sub.8 -C.sub.18 fatty acids; monoalkyl ethers of ethylene-propylene oxide copolymers known under the trade name of "UCON".RTM.; dibasic acid esters--chiefly sebacates and adipates; diesters of 2-ethyl hexanol such as di, tri or tetra ethylene glycol 2-ethyl hexanoate; esters of hexadecyl alcohol, particularly hexadecyl stearate (isocetyl stearate); silicone liquids--linear polymers of the organosiloxane family; liquid polyoxyalkylenes; and neopentyl polyol esters of which pentaerythritol ester is the most commonly used.
In the Dardoufas patent, U.S. Pat No. 3,687,721, there is disclosed a polyester yarn including a finish composition. This composition comprises 55-75 weight percent of the lubricant hexadecyl stearate, about 2 percent antioxidant and about 16 percent of a wetting agent including sulfated glycerol trioleate and an ethoxylated alkylamine. The finish composition further includes an HLB balanced emulsifier system including decaglycerol tetraoleate, glycerol monooleate and ethoxylated tall oil fatty acid. It is further disclosed in the Dardoufas patent that the hexadecyl stearate lubricant may be replaced with up to 50 weight percent of a rearranged triglyceride having C.sub.11 to C.sub.17 fatty acid chain members.
In U.S. Pat. No. 4,105,568, issued to Marshall and Dardoufas on Aug. 8, 1978, there is disclosed a finish for polyester yarns which is related to that disclosed in the previously cited Dardoufas patent. In the Marshall and Dardoufas patent, the yarn is first treated with a composition including 10-20 percent coconut oil, 10-20 percent stearic acid ester, 3-6 percent ethoxylated tallow amine, 10-20 percent ethoxylated lauryl alcohol, 8-12 percent of a sodium salt of an alkylarylsulfonate, 1-3 percent dinonyl-sodium-sulfo-succinate, and 35-50 percent white mineral oil. The yarn is then subsequently treated with a composition similar to that disclosed in the Dardoufas patent 3,687,721.
A textile treating emulsion is disclosed in U.S. Pat. No. 3,470,095 issued to Pontelandolfo on Sept. 30, 1969. The emulsion comprises a triglyceride of higher fatty acids, hydrogenated tallow fatty acid, a mixed ester of glycerol and an ethoxylated castor oil. The Coats patent, U.S. Pat. No. 3,248,258 issued on Apr. 26, 1966, discloses a nylon yarn finish including as a lubricant from 90 to 97 percent of a glyceryl triester such as coconut oil, glycerol triacetate and glycerol trioleate, and 3-10 percent of a non-ionic surfactant.
There are many other patents in this field which disclose finish compositions for various yarns or textiles. Other patents disclosing various finish compositions include the following: U.S. Pat. No. 4,126,564, issued to Marshall et al. on Nov. 21, 1978, disclosing a composition of coconut oil, polyoxyethylene, castor oil and ethoxylated tridecyl phosphate; No. 4,019,990, issued to Marshall et. al on Apr. 26, 1977, utilizing polyalkylene glycol and antioxidant; No. 3,853,607, issued to Iyengar et al. on Dec. 10, 1974, including polyorgansiloxane oil, wax and dialkyl phthalate oil; No. 3,672,977, issued to Dardoufas on June 27, 1972, disclosing a composition including hexadecyl stearate, coconut oil, ethoxylated tallow amine, ethoxylated lauryl alcohol, and white mineral oil; No. 3,113,369, issued to Barrett et al. on Dec. 10, 1963 including wax, a fatty acid ester lubricant and emulsifiers; and No. 2,964,470, issued to Wentworth on Dec. 30, 1960 disclosing a composition including polyoxyethylene ether and trimethyl quinoline.
Further examples of formulations in use or under consideration for tire cord include the following. It will be observed that fossil fuel derivatives continue to be a major source of ingredients for finishes for polyester tire yarn. In U.S. Pat. No. 3,387,966, issued to Morana et al. on June 11, 1968, it is recommended to use a specific antioxidant and a diester of the formula R--(O--CH.sub.2 --CH.sub.2)n--O--R, where R is 2-ethylhexyl and n is an integer from 3 to 7. In U.S. Pat. No. 3,464,922, issued to Bernholz et al. on Sept. 2, 1969, the use of trimethylolalkane (e.g. trimethylolethane) esters on synthetic linear organic polymer filaments is taught. In U.S. Pat. No. 3,962,516, issued to Marshall and Dardoufas on June 8, 1976, there is recommended a polyalkylene glycol compound of specific structure, known as UCON.RTM. products of Union Carbide Corporation. In U.S. Pat. No. 4,086,949, issued to Uy on May 2, 1978, the use of a solid lubricant, poly (vinyl alkyl ether) in the finish to impart good adhesion and fatigue resistance is disclosed. Other ingredients are phthalic acid esters, pentaerythritol ester, diundecyl phthalate, polyalkylene and microcrystalline waxes, etc.
There has also been a new universal demand for cleaner, uncontaminated air. In the United States there has been promulgated a stipulation that industrial plants, of which rubber tire manufacturers are typical, must severely reduce the content of noxious substances present in various emissions released into the atmosphere. Such regulations have now been adopted in all of the chief states where rubber tires are produced. These states have introduced legislation based on guidelines from the Environmental Protection Agency. The present invention provides an answer to these requirements.